Foam control in brown stock washing



Aug. 2, 1949. F. w. YOUNG FOAM CONTROL IN BROWN STOCK WASHING 4Sheets-Sheet l Original Filed Oct. 8, 1943 L35 inky IN V EN TOR. FTFAN/f WYJUNE ATTUHNEYS' .SWN

Aug. 2, 1949. F. W. YOUNG 2,478,150

FOAM CONTROL IN BROWN STOCK WASHING Original Filed 001;. 8, 1943 4Sheets-sheaf, 2

V INVENTOR. 5% NA W 2641MB ATTUHNE Aug. 2, 1949. w, YOUNG 2,478,150

FOAM CONTROL IN BROWN STOCK WASHING Original Filed Oct. 8, 1943 4Sheets-Sheet 3 1G. 8 -A FIG. 9 126 IN VN TOR. FFPANK W YUM/V5 Aug. 2,1949.

Original Filed 001;. 8, 1943 F. W. YOUNG FOAM CONTROL IN BROWN STOCKWASHING 4 Sheets-Sheet 4 FIGJZ INVENTGR.

YbL/NE' I Y ATTUENEYE' Patented Aug. 2, 1949 FOAM CONTROL IN BROWN STOCKWASHING Frank W. Young, Medfield, Mass.

Original application October 8, 1943, Serial No.

Divided and this application September 19, 1945, Serial No. 617,361

3 Claims.

This invention relates to methods and apparatus for recovering solidsfrom liquids in which they have been suspended, and washingthe solids sorecovered. More particularly, the invention relates to solids of such achemical nature that their recovery is rendered difficult due to theproduction of a troublesome foam during their manufacture and handling.Heretofore, no eiiective method or apparatus has been suggested forcontrolling or disrupting the foam bubbles, saving the liquor andobtaining a comparatively dry air.

This application is a division of my co-pending application, Serial No.505,478, filed October 8, 1943, now Patent No. 2,431,009, dated November18, 1947.

In the washing of brown stock (caustic sulphate wood pulp) in kraftmills, it is necessary at the present time, after the wood has beendigested in the caustic liquid, to wash the resulting pulp free of thecaustic liquor, resin and other impurities that have been disassociatedby the digesting process. For reasons of economy, it is of advantage torecover the major portion of the caustic liquor for reuse. This hasheretofore been done by washing the pulp in diffusers or wash pans andhas required large and expensive equipment and considerable laborbecause of the large quantity of foaming liquid present. More recently,the pulp has been washed on continuous filters by countercurrent washingusing, for instance, two filters for two stage countercurrent washing,three filters for three stage countercurrent washing, and so on. Thelatter method of washing reduces labor and decreases the loss of causticbut the handling and rehandling of the pulp and liquors in each washingstage causes considerable and very troublesome foam. Because of thisfoam, the pumps, tanks and other equipment in the system as a whole arevented into a plurality of foam tanks or traps, many of these beingneeded and much space being occupied.

One object of the present invention is to perform multi-stagecountercurrent washing of brown stock on a single filter withoutobjectionable foam.

A further object of the invention is to reduce and maintain to a minimumthe amount of foam produced in the recovery of caustic by washing.

In carrying the invention into effect, it is preferred to utilize afilter such as shown in copending application Serial No. 291,083 filedAugust 19, 1939, now Patent No. 2,352,303, issued June 27, 1944. Allaccessory equipment used with the filter or series of filters ishermetically sealed, the gaseous medium removed from the filter beingreturned to the filter for use in cake discharge.

It is a further object of the invention to utilize fluid withdrawn fromthe filter in the filtering operation to prevent the return of foam withthe cake discharge or blow-back air.

The invention also seeks methods and apparati for carrying out themethods, which are practical from the standpoint of ease and cheapnessof installation and practicability in use.

These and other objects of the invention and the means for theirattainment will be more apparent from the following detailed descriptiontaken in connection with the accompanying drawings illustrating oneembodiment by which the invention may be realized and in which:

Figure 1 is a somewhat schematic view showing one form taken by theapparatus of this invention and illustrating a continuous filter bywhich multi-stage washing in accordance with the process of thisinvention may be performed;

Figure 2 is a simplified view showing the structure illustrated in theupper right hand portion of Figure l to which mechanical foameliminating means has been added;

Figure 3 is a vertical sectional View showing details of the mechanicalfoam eliminator of Figure 2;

Figure 4 is a plan View of the foam disrupting element of Figure 3;

Figure 5 is a fragmentary view on an enlarged scale showing details ofthe Figure 3 construction;

Figure 6 is a diagrammatic view showing a modified form of foamdisrupting device;

Figure '7 is a fragmentary view looking from below in Figure 6;

Figure 8 is a fragmentary view of the structure shown in Figure 2illustrating the application of the tank and piping when a pulp washer(not shown) is used and in which fluid pressure is not utilized for cakedischarge;

Figure 9 is a modified form of the structure shown in Figure 12;

Figure 10 is a view showing automatic pressure regulation to balance thepressure in any two critical conduits;

Figure 11 is a diagrammatic view showing the tanks and pipe lines when avacuum filter pulp washer (not shown) is used in situations where thequantity of air carried down the barometric leg is. excessive andproduces considerable foam; and

Figure 12 is a diagrammatic view similar to that of Figure 11 butshowing a, single tank subdivided by partitions instead of threeseparate tanks.

Referring now to the drawings for a fuller understanding of the apparatiof this invention and the process by which foam is controlled: Thedigested or cooked pulp is blown into the blowtank l3! through the pipemarked blow. This pulp, as blown into the blow-tank, is 10 to 12%consistency, too thick to pump, and contains about ten pounds of dryfiber and pounds of liquor. In order to make this pulp thin enough sothat it can be pumped to the filter and so that it can be handledproperly on the filter, more liquor is added through the pipe I43. Thisis added to the bottom cone of the blow tank and is agitated with thepulp by the agitator I33. It has been found advisable to have thisdiluted pulp at a consistency of 2%. The stock, agitated in the bottomof the blow tank, is pumped through the line I49 by the pump I5I andenters the filter tank 46. This 2% pulp is stilltoo high a consistencyfor proper filtration. Therefore, further dilution is effected throughthe pipe line Hi5 so' that the mixture of 2% stock and liquor becomesbetween and one percent consistencyin tank 46. To maintain uniformoperation, and for ease of operation, an overflow is provided whichcarries t esurpius solution in tank at back to the blow tank throughpipe line IN. This is 'a small quantity and therefore thelow consistencyof this over-flow does not materially affect the consi teho in the blowtank. In any event thec'onsistency is still maintained.

A continuous filteradapted to perform multistage countercurrent washingof brownstock is shown in Figure 1 as comprising the filter drum I0rotatatbly mounted on a'n'a'xially extending cylindrical bearing member41. The filter drum rotates in the filtertank ts and the fil'ter'tank isOpen to the atmosphere. During operation, the filtrate is reiiioveo fromthe interior of the filter drurn through the hollow trunnion (beariii'tiehd-reusthrough the barometric leg :05.

in eration, the vacuum filter 'drum' If! picks up'the'st'ock,withdrawing the liquid through the filter ,wire, and maintaining afilter cake or stock ohtheoutside of'the drum according to the usualiii'ahh'e't or veouuih' filtration. In the upper part of therotation,medium wash liquor as trom n'ozzies a8; their week weight 'w'a'sh'liquor as from nozzles 81, and finally hot waterets from nozzle8'Ii','is opened in three-stage 'countercurrent' w'asli irig; "The washliquid fallingfsay from a nozzle 8 6 ahead oithe point where the cakeleaves the drum, passfe'sthrough'the filter cake on that seg- Ifieii'tofthedruih periphery and enters a pan 98 mounted therebeneath. Anoutletpipe 9'2 from h to p'ass'esinto and through thecyl in'drical pump97.

rior of the drum where it mixes with the filtrate and is evacuated bybearing pipe 41 and hard metric leg I05. This description is of a threejstagecountercurrent washing and to those versed in the art is known tobe heretofore regularly? The washed" accomplished by using threefilters. pulp is discharged from the'filter by the doctor 85;

Where a barometric leg is used, as at H15, for

producing the vacuum, air drawn through the filter medium is carrieddownwith the liquid in thebarometric leg I05 and into the closed tank; II8, where the air and liquid separate, the liquid" flowing out of theclosed tank I I8 through the pipe I20 which traps the air under pressurein the closed. seal tank H8 and controls the volume of air according tothe height of the outlet MI.

The air is accumulated in the upper part of the tank H8 at the pressureproduced therein and is "allowed free now through pipelines I21 and I2?tit into the blow-back pipe 58 leading to the air box' 62. Thus thevolume :of an 'anjdl-the pressure thereof produced in the closed tankII8 can be utilized in the air box 62 to discharge the filter cake.

It is proposed in accordance with one aspect of'the invention, to removethe filtered material frornthe surface of the filter drum by a pressuredifferential upon opposite faces thereof. To this'en'd, aconduit, suchas the pipe 56, adapted to conduct air orother gaseous medium underpressure from the pi' pe I22, is disposed within the cylindrical bearing4'! and an extremity 58 thereof terminates within the drum interior. Inthe illustrated embodiment, a shoe 62 receives fluid medium underpressure from this conduit 58. The cuts waii of the shoe is providedwith an aperture fi'd' 'of afsi'ze'ftojregister, say, with one of'the'passages in the'drum periphery.

I A yacuuih pump 121: is'use'd to exhaust the on from the filtefd'rum"and produce the vacuum;

filtrate; some teem is carried through 'thepip'e 12s by the v oiiirirpuhi I24"ah'dexha'fisted slow velocity foam coming up pipe I 27. Thisaction breaks up the to-em into' liquid the air, the liquid returns tothe te 'iethtough ipe 121, The

air, tre of foam, ti -v supthfoilfgh pipe I22 'eh'ti' enters theblowback pipeBB, "scent is used for discharge "o fthe 'filter'cake;

w to i rtth oeke;ofi'the-o tim 'pioo ie'es a slight'bac'k' pressurewhich; in turn, is exerted in Passing the blow-backa ir' thtoiigh thefilter the tank I I%f T is back pr ssure tends to hold" t e i oain'in tek i-i s ho"elicits 'ohiyeitto'ris'e in pipe m. e tor goirlgfeyoieof'opet'etioiis i ettie iiat y en otive whe'ie"a"sm'all filter is usedwith a'r'elativelylarge teak:

w ere i'er gefiiters ere i'iseoin the aforesaid mean-er, the tej k i;1-e1t'tti'veiy'Shh-e11 compete-d wit ft size r thefiitehjehu there'is'likely'to be en a'c'cuiniiiatibifoi foam and the increase in pressure intat-1: 19." 1h 'Ci'de1 to relieve the pressure in [I8 fah d prevehtroaih' passing out through the e ef I111; Figures, it is desirable todisrupt the foam "into" free' jair and liqiii'd.

washing, two objects are that'the inp- 'di's'; arg'ed; ov'erth'e doctoras'is' clean eiroug to tens d" form'akin'g taper, and second to 'reteili the is en an oi the'ehemic'al's tori" e; rhesefi o'oveiea orieihi'oeis, ooh sistin'g "pr mai'ilyfof ceus't'io 's'oda' aha causticsiilphate'areniifird with the wood ohi s iii the digester. After cooki gordigesting the wood which tohhs the phi'iiifth'e -emie is-ei e i i thel'i'quid miii'edwitht epiilbiwhich is blow'ii' into the new tank."A-eohiiehie thut ot absolutely 'er:

asuri iigjtheafnount of themicals 'in"the liq is by deejr'eeseauihe. Inthe illustrated emb diment; the Be'uj e of the liquor iii the blow tankiis sh -wris 15 This liquor, d1 w'n b'y vacuum through the filtr wire,and deliv the honor tank I39 from which themaio'r portion isreeirooiate-o i oro itit oh' h theb owtehk I7 3I' hnd'uil tiohih thefilter plus, which in gallorit rmite: T e sue, s the hot water wash oftank 139 to the etehorat'oi.

During rotation ofthe filter I 0, the sheet of pulp or filter cakecontaining liquor at Baum passes under the shower 88 containing liquorat about 6 to 8 Baum. In the most efiicient operation'this liquor at 6to 8 Baum displaces the liquor at 15 Baum in the sheet and the liquor at15 Baum enters the filter drum I0 and passes out of the barometric legI85. The pulp sheet, then containing liquor at 6 to 8 Baum passes underthe shower 81 where a weaker liquor at 2 to 3 Baum is sprayed on it anddisplaces 6 to 8 Baum liquor which is drawn out through pipe I00, pumpIOI and back to the shower 88. The filter cake or pulp sheet nowcontaining liquor at 2 to 3 Baum passes under the hot water shower 86where the hot water displaces the liquor, the liquor entering thecompartment 90 passing down the pipe 92, pump Ill, and pipe 95 to theshower 8I. ihe clean sheet containing water is discharged on the doctor85. appreciated that in actual practice, 100% washing is not obtained.Therefore, the sheet coming oil at 85 does not contain pure water. Thereis a slight soda content. This soda is lost. Some wash water passescountercurrent through the other stages and this will reduce the Baume'of the liquor in the filter tank from 15 Baum to about 14 Baum as itcomes out of the liquor tank I39 and goes to the evaporator.

In the evaporator, the water is boiled off from this liquor at 14 Baumthereby raising it to, say, or 40 Baum-, and it is returned to thebeginning of the cycle, that is, it is mixed with the wood chips andcooked. The wood chips contain water and water reduces Baume again so beeliminated from entering prior to the delivery i of liquor to theevaporator or for recirculation in the apparatus. One suchinstrumentality, the foam eliminator, is illustrated in Figure 3 whereinthe foam or bubbles rising in tank I53, Figure 2, pass out through thepipe I and into the foam eliminator I56 where they come in contact withthe slotted disc or fan I64 rotating at high speed. This fan I64 breaksor disrupts the hubbles into small drops of liquid, which drops arethrown off by centrifugal force against the deilector plate surface I88,Figure 5, so that the liquid flows down the side walls of the pipe I55back into the tank I58. The air passes out to atmosphere through thepipe I I8.

When the foam eliminator is used in connection with a vacuum filterwasher, Figure 2, using air blow-back for cake discharge, the liquidfrom the filter I0 passing through the trunnion 41 is carried down thebarometric leg I95. The air containing foam is drawn from the top of thebarometric leg through the pipe line I23, through the vacuum regulatingvalve I12 to the vacuum pump I24, discharges from the pump through thepipe I28 at high velocity into the Y I28, I29. The liquid and foambubbles striking the opposite side of the Y I28 fall into the tank I58through the pipe I Id. The air, following the path of lowest pressure,travels, free of foam, up the pipe I22 into the conduit 55 of the filterwhere it is used for discharging the filter cake. This separation offoam and air will take place in Y I28, I29 provided the pressure in pipeI14 is slightl less than the pressure in pipe I20. The pressure in tankI53 and pipe I74 is maintained less than the pressure in line I26 byventing some It will be air out of the top of the tank through pipe I55and the foam eliminator I56. To prevent the venting of too much air,which would result in the pressure in the pipe I22 being insufficientfor cake discharge and so that the amount of air vented wil not be inexcess of that which can be handled by the foam eliminator, a valve I76is placed in pipe I18 to control the volume and the pressure and theclean air is vented to atmosphere through the open end of pipe Ill,

The barometric leg I05 is sealed by maintaining a constant level, I18,of liquid in the tank I53 by action of the float I19 acting throughlinks and levers on the valve I 88, allowing the liquor to flow out ofthe pipe I8I to, as in the case of kraft black liquor, the evaporatorfor re-use.

In the washing of kraft stock, the black liquor is hot, frequently about200 F. This strong caustic liquor has been diluted with water in thecooking process and in the pulp washing operation. Such water must beevaporated from the recovered liquor before re-use. It has been foundthat, in the instant invention, the foam eliminator I56 breaks the foambubbles into small particles of concentrated liquor and small particlesof water. The small particles of water at this, almost boiling,temperature are turned into steam or fog so that, in this instance, theeliminator emits Water vapor and air, and not dry air. Therefore, thefoam eliminator in this situation has a further advantage, in that itaids in the concentration of the black liquor and reduces the work ofthe evaporator. 7 When the foam eliminator is used in connection with avacuum filter washer not using air blow-back for cake discharge, Figure8, the operation is the same as that just described except that the airtraveling up pipe I22 does not go to the filter trunnion but passesthrough a pressure regulating valve I83 and then through the pipe I84 toatmosphere.

When air bubbles and entrained air are carried down the barometric legin considerable quantities, which is usually the situation except 5 whenthe barometric leg is of such exceedingly large diameter that thevelocity of the falling liquor is very slow, this large quantity of airand foam must be handled separately and preferably in a manner similarto the exhaustion of the air and foam from the vacuum pump. Tank I53 isthen used only for handling the discharge from the vacuum pump, seeFigure 11, and an additional tank I86 takes care of the exhaust from thebarometric leg I05. The air and foam are removed from the top of tankI86 through the pipe I88 entering a Y I 89. Here, the liquor and foambubbles, striking the opposite side of the Y I89 fall into tank I90through the pipe I92. The air, following the path of lower pressure,travels, free of foam, up the pipe I94 into the T fitting I95 where theair unites with the air coming through the pipe I96 from the tank I53and is directed through the pipe I 98 to the filter for use as blowbackair or the air ecapes through a pressure regulating valve (not shown) toatmosphere. The pressure in tank I99 is maintained slightly below thepressure in pipe I86 by venting some air out of the top of the tank I 90through the pipe 280, a foam eliminator I56 and pipe 203. The liquorsettling from the foam from pipes I14 and I92 into tanks I53 and I90,respectively, and the liquor broken down by the foam eliminators whichsettles in the bottom of the tanks I53 and I90 is drained into tank I86by the pipes 7 205 and 206 that are sealed b'elow t-he level of theliquor-201.

An improved method for handling the air and foam exhausted fromthevacuum: pump and exhausted from the barometric leg is shown in Figure12. Tank I53 is divided-into'two'parts by the partition 208 andthe airand'lfoam in the exhaust from the vacuum pump areseparated'by the Y I28,Y I29 in the same 'manner'as described in connection "with Figure 2 andthe liquor and foam is collected inthe upper part 204 of tanki' 153.

"Thefoam: accumulating in} the bottom part 239 of 'the 'tank I53 iscarried'by the air-'from-t'he barometric leg'IG5 up the pipe 2H and intothe Y 2I3. There the liquid. and foam bubbles strikihgzthe'oppositeside-of the V213 fall into the upper part1 204 of'the tankl53'through-'the'pi-pe 2I5. The air, following the path of-lowest-pressure,itravels, free of foam, up the pipe *2II5, similar to the action in YI29 and pipesIZZ-and I26. ."Ihe air'through the pipes 2 I6 and 122enters theIT 'I95 andthen'trav'els throu'gh the pipe I 98 to theblow-back discharge of the filter or through arpressure regulatingvalve'to atmosphere. The liquors settling from the foam from pipesZ Iiiand 2Hand thel-iquors broken-down by the foam eliminator coming down pipe I55col1ect-in-the bottom of the upper part 204 of tank I53 and now downthrough the-pipe 2I 8 that is sealed in the bottom of tank '53 and flowsout with the'rest of the liquor tli'rough the valve I'80- as operated-bythe the float I19.

The-foregoing voperation is rather critical. If

the pressure inpipe 2 I5 is greater than'the' pres- L,

Thelfoam and. bubbles rising in 'atank ZZB-enter the compartment orextension"thereof-..221rand come in contact withflat, f-an shapedjets-2350f steamer .other fluid and; are disrupted thereby. The air.freed from the-foamand bubbles passes through the sprays 229-and isevacuated'through the pipe 231, the liquid will not pass through thesprays and 'falls as arain226 into thetank 22-5; The sprays. areproduced by passing steam or other "fluid through pipes 233 andfan-shaped spray producing jet nozzles 23 5. This-type of foameliminatorwhen used on black liquorfoam (kra ft pulpprocess) gives re's'ultssubstantially equal to those obtained withthe mecharncahfoan leliminator (Figure 2) "although the addition of theavaterpondense'd fromthesteam is detrimental to the strength of the black liquor. 'Inirespect of man-y f 0am problems, however, the addition of such water orother'fiuids is not harmful.

Figure illustrates instrumentalitiesto automatically control thepressure inpipe2tl, Figure 1-2, and equivalent conduits, so -'that'ft hepressure in pipe 2I'5 equals or does not-exceedthatin'pipe 2H. 'JBy'moving the butter fiywalve era a ccrqingxto pressure on a diaphragminstead of setting theiweig'htZZh-a diaphragm"c'hariiber 2 39 i splabedin the upper portion" 2 04 of tank I53 or' outside, with a pipeconnected to openiiig'flfi' 'a' nd tank I53. The diaphragm chamber' is'connected by pipe 24 I td-the pipe-2 I I above -the"butterfiy"va'lve228. Whenthe: pressure in the-upperspart of pipe2II-eXceeds the pressurein'theipipefll, which is also thepressure'in the' upper part' of tankI53, this pressure is transmitted through pipeMI to the upper-side ofthe diaphragm 243 and pushes-the diaphragm 243 downagai'nstth'e pressurein the tankadmitted to theunder side of the-diaphragm 243 through theopening 245. When the diaphragm 243 moves downwardly 'it carries plunger24! downwardly, which plunger, through a link and leversystem,-indicated generally at 249, pushes the arm 253 to close thevalve 220 until the pressure in the upper part of-pipe 2 I I equals thepressure in the pipe 2 I I, whereupon the valve 220 is again opened bymotion in the oppositedirectionof arm 253 when the pressure in the upperpart of pipe 2I I is less than the pressure in the pipe 2!! or in theupper part of tank I53 which pressure tends to push the diaphragm 243up. Obviously instead of the hole '245 in the chamber 239 communicatingwith the interior of the tank I53, the chamber 239 may be locatedoutside of the tank I53, with a pipe connecting the opening 245'and theinside of the tank I53.

A modification of the structure-shown in Figure 12, although involvingsubstantially the same principles of operations, is illustrated inFigure' 9. Here a pipe. 2| I, conducting gaseous media, includingbubbles and foam, from a lower portion of the tank I53, is. reverselybent as at 3I3 and joins the pipe I25 conducting gaseous medium and foamto and through-the Y I29. As before,-th'e bubbles of foam are broken upin the Y I29 and the liquor falls into the tank I53, while the air,

reversing direction, free from foam, travels at high velocity intoslightly lowerpre'ssure up'th'e pipe I22.

It will thus be seen-that methods of and-apparatus for theseparation ofair arid liquid, initially a combined as-b'ubbles or foam,'is providedby this invention. This foam is most pronounced inthe handling of brownstock. The separation ofthe air and liquid may be efi'eete'd by variousinstrumentalit'iesin any of which however, the foam or bubbles aredisrupted whereby the air and the fluid inwhich the air is entrapped arecaused to separate, the air being encouraged to go in one direction andthe fluid, free of air, encouraged to go in a different direction.

Variousmodifications will occurto those skilled in the art intheconfiguration and disposition of the instrumen'talit-ies by which-thegaseous'an'd fluid media are caused in this field, to separate, afterapplicant has herein been the first to point the way and no limitationis intendedby the phraseolo'gy of the foregoing description 'or"illustrations'in the accompanying drawingsexcept as indicated inthe'annexed claims.

What is'claimed is:

1. Apparatus for the elimination of-foam, com prising a seal tank, atransverse partition I in said tank defining an upper chamber and alower liquidcontaining chamber, a barometric leg delivering liquid intosaid lower chamber, a foam breaking chamber including'a- Y-inl et,anoutlet from said foam breakingchamber into said upper chamber,a'con'duit for conducting air containingfoam from the lower chamberupwardly'into an upward arm, across and downwardly thpu said Y-inle'tinto said foam breaking chamber, the

liquid from which drips down through said outlet into said upperchamber, a conduit connected to the top of said foam breaking chamberfor conducting air free from foam upwardly and horizontally into a T, apump, a second foam breaking chamber including a Y-inlet and a secondoutlet connected with the top of said upper chamber, a pipe forreceiving air, liquid and foam from said pump at high velocity anddelivering same into the Y-inlet of said second foam breaking chamber,the liquid from which falls through said second outlet into said upperchamber, an air conduit connected to the top of said second foambreaking chamber for conducting air free of foam upwardly andhorizontally into said T, and a third outlet connected to the top of theupper chamber for the escape of foam.

2. The combination as claimed in claim 1, additionally including a foameliminator connected with said third outlet, said foam eliminatorincluding an air exhaust and foam conduit, and a driven wheel in saidfoam conduit positioned in a plane transverse to the direction of travelof the foam therein, for breaking up foam passing therethrough.

3. Apparatus for the elimination of foam, comprising a seal tank, atransverse partition in said tank defining an upper chamber and a lowerliquid containing chamber, a pipe connected with the lower part of theupper chamber for conducting liquid free of foam into said lowerchamber, a barometric leg delivering liquid into said lower chamber, afoam breaking chamber including a Y-inlet, an outlet foam said foambreaking chamber into said upper chamber, a conduit for conducting aircontaining foam from the 10 lower chamber upwardly into an upward arm,across and downwardly through said Y-inlet into said foam breakingchamber, the liquid from which drips down through said outlet into saidupper chamber, a conduit connected to the top of said foam breakingchamber for conducting air free from foam upwardly and horizontally intoa T, a pump, a second foam breaking chamber including a Y-inlet and asecond outlet connected with the top of said upper chamber, a pipe forreceiving air, liquid and foam from said pump at high velocity anddelivering same into the Y- inlet of said second foam breaking chamber,the liquid from which falls through said second outlet into said upperchamber, an air conduit connected to the top of said second foambreaking chamber for conducting air free of foam upwardly andhorizontally into said T, and a third outlet connected to the top of theupper chamber for the escape of foam.

FRANK W. YOUNG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,176,428 Callow Mar. 21, 19161,967,938 Jantzen July 24, 1934 2,140,811 Poole Dec. 20, 1938 2,184,195Naucler Dec. 19, 1939 2,231,544 McCorquodale et al. Feb. 11, 19412,257,945 Fraser Oct. 7, 1941 2,335,641 Buckley Nov. 30, 1943 2,352,304Young June 27, 1944

